Fruitarians adhere to a diet that consists entirely or primarily of fruits in the botanical sense, and possibly nuts and seeds, without animal products. Fruitarian is a subset of dietary vegan. A fruitarian way of life may be adopted for different reasons, including ethical, religious, environmental, cultural, economic, and health reasons. There are many varieties of the diet. Some people whose diet consists of 75% or more fruit consider themselves fruitarians. Some fruitarians will eat only what falls (or would fall) naturally from a plant: that is, foods that can be harvested without killing or harming the plant. These foods consist primarily of culinary fruits, nuts, and seeds. Some do not eat grains, believing it is unnatural to do so, and some fruitarians feel that it is improper for humans to eat seeds as they contain future plants, or nuts and seeds, or any foods besides juicy fruits. Others believe they should eat only plants that spread seeds when the plant is eaten. Others eat seeds and some cooked foods. Some fruitarians use the botanical definitions of fruits and consume pulses, such as beans, peas, or other legumes. Other fruitarians' diets include raw fruits, dried fruits, nuts, honey and olive oil, or fruits, nuts, beans and raw chocolate.

Some fruitarians who espouse Judeo-Christian beliefs hold that being a fruitarian was the original diet of humankind in the form of Adam & Eve, based on an uncommon interpretation of the Book of Genesis 1:29. They believe that a return to an Eden-like paradise will require simple living and a holistic approach to health and diet. Some fruitarians wish, like Jains, to avoid killing anything, including plants, and refer to ahinsa (nonviolence) fruitarians. Some fruitarians say that eating some types of fruit does the parent plant a favor and that fleshy fruit has evolved to be eaten by animals, to achieve seed dispersal. For some fruitarians, the motivation comes from a fixation on a utopian past, their hope being to return to a past that predates an agrarian society, to when humans were simply gatherers. Another common motivation is the desire to eliminate perceived toxicity within the body. For others, the appeal of a fruitarian diet comes from the challenge that the restrictive nature of this diet provides.